Apparatus for incubating eggs



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APPARATUS FOR INCUBATING EGGS Filed Aug. 11, 1961 8 Sheets-Sheet '7INVEN TOR. 927/102 M. THE/L16- uMJM p 8, 1964 A. w. THEILIG 3,147,737

APPARATUS FOR INCUBATING EGGS Filed Aug. 11, 1961 8 Sheets-Sheet 8 ak kR INVENTOR.

Y Her/we n. 7595/4/6- United States Patent 3,147,737 AhPARATUS FGRKNCUBATTNG EGGS Arthur W. Theilig, Fort Atkinson, Wis, assignor toRockwood 8: Co., Chicago, ill., a corporation of Delaware Filed Aug. 11,1961, Ser. No. 130,819 6 Claims. or. 119-35) This invention relates toan apparatus for incubating eggs and to auxiliary apparatus used inconnection therewith.

One of the best known and most successful prior art techniques ofincubating eggs is the subject of United States Patent 2,603,182. In theincubator of the said patent, all of the eggs are placed in theincubator at the same time, all eggs progress concurrently through thevarious stages of incubation and all are removed together afterincubation.

Eggs require heat in the early stages of incubation (for chicken eggs,the first fourteen days) and will give off heat in the final stages ofincubation (the last seven days), and will require oxygen and releasecarbon dioxide in all stages of incubation. This means that eggs indifferent stages of incubation require different ambient tempera tureconditions for proper hatching. Inasmuch as all of the eggs in the priorart incubator aforesaid are at the same stage of incubation, temperatureconditions within the incubator can be very closely controlled throughthe different stages of incubation and will result in a high percentageof hatchability of the eggs therein.

Another technique of incubation is to use very large incubators, whichcontain eggs in different stages of incubation. Each egg tray must beclearly marked so that it will be taken out of the incubator at theappropriate time (on the eighteenth day of incubation in the case ofchicken eggs) and shifted to a hatcher. An advantage of a multi-stageincubator is that the heat which is given off by the eggs in their finalstage of incubation is absorbed by eggs in the initial stage ofincubation so that the overall requirements for heat are reduced.However, multistage incubators are subject to the difficulty ofmaintaining accurate control over the temperature in the vicinity of anyegg tray and in prior art multi-stage incubators known to me, theattempt is made only to maintain the average temperature constantwithout regard to the precise temperature requirements of the eggs intheir various stages of incubation.

The incubator of the present invention achieves the advantages of closecontrol over the actual temperature of the eggs in their various stagesof incubation and at the same time employs an entirely new concept oforganizing and handling the eggs within the incubator to expeditetransfer of heat from late stage eggs to early stage eggs. Thus theadvantages of multi-stage incubation are achieved without loss ofcontrol over the temperature of eggs in their different stages ofincubation.

This is accomplished by arranging egg racks in the incubator cabinet inrows according to the stage of incubation of the eggs in the rack andcirculating the air around the eggs in a pattern in which the air willflow from the late stage eggs to the early stage eggs, thus to transferheat from those eggs giving off heat to those which will absorb it. Thisreduces the heat demand of the incubator cabinet very materially and yetthe temperature of each rack of eggs can be very closely controlled atthe optimum value according to the stage of incubation thereof.

The present invention also employs an entirely new concept inhandlingthe eggs to eliminate transfer thereof from one container toanother. An entirely new egg tray is used in which the eggs are placedin the laying house Where the eggs are gathered. This egg tray istransferred bodily to the incubator and the eggs need not be touchedagain until they are removed from the incubator and transferred to thehatcher. In this manner, the eggs are trayed at the laying house andhandling costs thereafter are materially reduced.

The egg trays of the present invention are characterized by theirrelative durability and rigidity, as compared to the disposable moldedpulp fiber trays heretofore standard in the industry. The new tray hasminimum contact with the eggs so that practically all (at least percentin the disclosed embodiment) of the egg surface is exposed to the flowof air thereover. Accordingly, when in the incubator, very close controlof the temperature of the egg can be obtained by the high rate of heattransfer between the egg and the air.

Another advantage of the novel egg tray of the present invention is itsincreased capacity. It will accommodate thirty-six eggs per tray, ascompared to thirty eggs per tray which has heretofore been standard formolded pulp fiber trays.

Other objects, advantages and features of the invention will appear fromthe following disclosure in which:

FIG. 1 is a perspective view of the new egg tray viewed from the top.

FIG. 2 is a perspective view of the new egg tray viewed from the bottom.

FIG. 3 isan enlarged fragmentary plan of the egg tray of FIG. 1.

FIG. 4 is a fragmentary side elevation of the tray shown in FIG. 3.

FIG. 5 is a fragmentary vertical cross section taken along line 5-5 ofFIG. 3 and through stacked egg trays showing the interfitting of therespective standofl' posts of the trays.

FIG. 6 is a fragmentary cross section taken along the line 66 of FIG. 3.

FIG. 7 is a cross section taken through a shipping carton with stackedtrays embodying the invention showing how the egg trays of the presentinvention fit within the shipping carton.

FIG. 8 is an end elevation of anegg rack in which trays of eggs aresupported within the incubator cabinet.

FIG. 9 is a fragmentary cross section taken along the line 9-9 of FIG.8-.

FIG. 10 is a fragmentary perspective of the rack of FIG. 8, side and topwalls thereof being removed to expose details.

FIG. 11 is a perspective view of an egg tray pallet by which the traysmay conveniently be loaded into and unloaded from the rack of FIGS. 8through 10.

FIG. 12 is a diagrammatic view in perspective illustrating how thepallet of EEG. 11 is used to load egg trays into the rack.

FIG. 13 is a diagrammatic perspective view illustrating how the palletis removed from beneath the trays of eggs after they have been loadedinto the rack.

FIG. 14 is a diagrammatic view illustrating how the egg trays arelowered from the transfer pallet into support relationship to the tracksof the rack.

FIG. 15 is a diagrammatic perspective view of an incubator cabinetembodying the present invention with egg racks within the cabinet and inthe course of movement thereinto, portions of the cabinet walls beingbroken away to expose the interior thereof.

FIG. 16 is a longitudinal vertical cross section taken through theincubator of FIG. 15.

FIG. 17 is a horizontal cross sectiontaken through the incubator of FIG.15. p

FIG. 18 is a transverse vertical cross section taken through theincubator of FIG. 15.

FIG. 19 is a diagrammatic view showing the air flow pattern over trayedeggs as the trays are inclined to the direction of air flowlongitudinally through the incubator.

FIG. 20 is a diagrammatic view in cross section showing the air flowpattern through the incubator when the air inlet and outlet ports areset for minimum air intake.

FIG. 21 is a view similar to FIG. 20, but showing the dampers for theair inlet and outlet ports in a more widely open position.

FIG. 22 is a diagrammatic view indicating the mode of interconnectingthe fluid motors for the egg turning mechanism to the source of fluidpressure therefor.

FIG. 23 is a view partly in vertical cross section and partly inelevation of a track, switch and caster wheel of an egg rack.

FIG. 24 is a view partly in elevation and partly in section showing aground wheel of a rack on its track.

FIG. 25 is a plan view of a track switch over which the racks are movedin the course of changing the direction of rack travel.

The Egg Trays An important feature of the present invention resides inthe structure of the egg tray shown in FIGS. 1 through 7 and in whichthe eggs are placed immediately after gathering in the laying house andfrom which they need not be removed until incubation has beensubstantially completed and the eggs are transferred to the hatcher. Theegg tray of the present invention greatly improves on the conventionalmolded pulp fiber trays heretofore used and which were ordinarilydiscarded after a single use.

The typical prior art pulp tray required dividers between each tray,large surfaces of the egg were in contact with pulp surfaces of the trayso that free circulation of the air was not possible thereabout and theeggs had to be removed from the pulp trays and placed into specialincubating trays.

According to the present invention, however, the egg trays are made ofdurable heat and moisture resistant, reusable material, desirably amolded plastic in which the eggs are supported on widely spaced pointsof contact with tray support members, substantially all of the surfaceof the egg being exposed to the air to provide free circulation of airabout the eggs when in the incubator.

Moreover, each tray is provided with standoif feet on which one tray issupported in spaced relation to the next tray. Accordingly, no dividersare needed between stocked egg trays of the present invention. Inaddition to the superiority of the trays of the present invention, fromthe standpoint of rigidity, reusability, resistance to heat, moistureand egg washing solutions and substantially complete exposure of eggsurfaces to circulating air, the trays of the present invention willhold more eggs within the same perimeter. Egg trays of the presentinvention will hold thirty-six eggs per tray, as distinguished from theprior art molded pulp fiber trays which hold only thirty eggs.Accordingly, more eggs can be handled at the same time and without anyneed for increased space in the egg shipping cartons, etc.

As shown in FIGS. 1 through 7, the tray is molded of plastic material. Iprefer to use polypropylene, which is a plastic material characterizedby low shrinkage and high memory. Accordingly, if the tray is deformedbecause of mechanical stresses, it tends to quickly return to itsoriginal configuration and is not materially affected by heat. The tray30 consists of a perimetrical rim 31, which has a square outline inplan. The interior of the tray is subdivided into thirty-sixsubstantially identical cells disposed on a discontinuous circle ofappropriate size to provide a support cradle for the small end of theegg 34, as shown in FIG. 5. The ledges 35 are relieved to providepassages 36 through which air may freely flow over the eggs and throughthe tray. Accordingly, the egg 34 has only discontinuous line contactwith the edges of the ledges 35 in its normal position shown in FIG. 5in which the small end of the egg is down and its large end isuppermost. This disposes the air sac of the egg uppermost where itshould be for proper incubation of the egg.

, Strut and rim portions which bound the respective cells 32 are alsoprovided with upwardly projecting fragmentary fin-like partitions 37which extend upwardly just beyond the greatest transverse dimensionthrough the conventional egg 34 and which prevent lateral abutment ofthe eggs and provide support for the eggs when the trays are tilted asshown in FIG. 19. The fragmentary partitions 37 are widedy spaced, as isclear from the drawings, to provide open spaces 39 therebetween for freeflow of air around the eggs. The voids 38 (FIG. 5) formed at the base ofeach partition 37 are optional and are provided primarily to save onplastic material in the fabrication of the trays.

To facilitate stacking one tray upon the other, each tray 30 is providedwith four downwardly projecting hollow tubular legs 41 and axiallyaligned upwardly projecting hollow standoif legs 42. The legs 41, 42 ofnext adjacent trays in a stack intersect in telescopic relationship, asshown at the joint 43 of FIG. 5, so that when packed in the shippingcarton 44 of FIG. 7, the eggs 34 will be properly spaced, bothvertically and horizontally and protected against contact with eachother and from the sides of the carton.

The rim 31 of the tray 31) is desirably provided with finger gripindentations 45 to facilitate handling the tray in the course ofremoving it from the carton 44, placing it in the incubator racks, etc.

Egg trays fabricated according to the present invention are considerablymore rigid and form-sustaining than the molded pulp fiber trays of theprior art and can be reused almost indefinitely for the transport ofeggs between the laying house and the hatchery and in the incubator, aswill hereinafter appear. The rigidity of the tray is attributed to thestructural strength of the struts 33 and rim 31. If desired, some of thestruts 33 may be of different cross section than other struts in orderto provide different strength characteristics.

Inasmuch as the eggs are supported primarily on the cradle ledges 35,the respectively tray cells 32 are adapted to receive eggs of almost anysize typically found in laying houses. Eggs of different sizes willsimply assume 1 different positions and levels in the trays, dependingupon or cubicles 32 by transversely related struts 33 which inthe levelat which they contact the cradle ledges 35.

The Egg Rack When the eggs arrive at the hatchery in the cartons 44, theegg laden trays 30 are removed therefrom and are placed in egg racks 46,as shown in FIGS. 8 through 14. When loaded the racks are transferred tothe incubator cabinet 47 shown in FIG. 15.

The racks 46 consist essentially of a skeleton frame having corner posts50 supported on a base frame 51, the entire rack being movable onmedially grooved caster wheels 52 along the floor or the tracks 53 whichare on the floor of the cabinet 47.

The respective racks 46 further comprise multiple hanger assemblies onwhich loaded egg trays are supported for turning. As best shown in FIGS.8 and 9, each rack 46 has oppositely disposed headers or cross beams 54on which cross shafts 56 are journalled for rotation in the bearingblocks 57. These cross shafts 56 bear the weight of the turning hangerassemblies which are suspended therefrom. At corresponding respectiveends of each of the cross shafts 56 there are welded or otherwisesecurely fastened transverse rocker arms 55, 58. The rigid trayreceiving tracks 66 which desirably consist of angle irons.

The hanger brackets 64, 65 and egg supporting tracks 66 are adapted tobe tilted between opposite inclinations of 45 to the vertical underpower of the double acting fluid motor 67, the piston 68 of which actson the tie bar 69 which is pivotally connected to the apices of therespective triangularly shaped rocker brackets 55 thus to tilt eachrocker bracket 55, 58 about the axis of its shaft 56. Fluid motor 67 isanchored on the bracket 72 which is mounted on a rack frame member 73.

Accordingly, egg trays supported on the track 66 can be turned through45 in either direction, one such position being shown fragmentarily inFIG. 16. In this way the eggs are turned to prevent adhesion of theembryo to the shell, as is necessary in egg incubation.

The eggs are turned about once every hour from 45 inclination at oneside of the vertical to 45 inclination at the other side of thevertical. The motor 67 is accordingly energized in one direction or theother once every hour.

To stabilize the hanger assembly during this turning movement, selectedhanger brackets 64, 65 are pivotally connected on pins 74 at theirmidpoints to cross straps 75 which are rigidly connected to the corneruprights 50. This prevents side sway of the hanger assemblies within theracks 46.

The Egg Tray Loading Pallet The egg trays 30 are loaded into the racksmost expeditiously by use of the tray loading pallet 76 shown in FIGS.11 through 14. The pallet consists of a sheet bed 77 with one end turnedup to form a finger gripping handle 78. Slightly inwardly spaced fromits side margins, the sheet bed 77 has upwardly open channel members,each having a high flange 81 and a low flange 82. As shown in FIG. 14flanges 82 are spaced apart slightly less than the spacing of tray posts41.

Egg laden trays 30 which have been removed from the carton 44 of FIG. 7are set in end to end relation upon a pallet 76 and receive support fromthe high channel flanges 81 on which the cross struts 33 and rim 31 ofthe tray will rest between adjacent egg rows, as shown in FIG. 14. Thedownwardly extending posts 41 of the trays will embrace the low flanges82, as is also shown in FIG. 14, thus to align the trays 30 in end toend relation on the pallet and keep them from slipping laterally.

The sheet bed 77 of the pallet is just wide enough to be received on thebottom flanges 83 between the hanger tracks 66. Accordingly, the entireegg tray laden pallet can he slid onto one set of hanger tracks as shownin FIG. 12 by slidably engaging the pallet with the tracks 66, 83 andmoving it in the direction of arrow 84.

Note that the flanges 81 of the pallet 76 are high enough to hold thetray ribs and struts 31, 33 out of contact with the hanger tracks 66while the pallet 76 is being slid onto the rack. When the egg trays 30are completely within the rack, the operator can place his fingeragainst the endmost tray 30, as shown in FIG. 13, and then withdraw thepallet 76 from beneath the egg trays 30 by pulling it in the directionof arrows 85.

The respective ends of the channel flanges 81, 82 are tapered at theirends, as indicated at 86. Accordingly, as the pallet is withdrawn, asshown in FIG. 13, the trays 30 will be permitted to descend by gravityuntil the tray is supported solely on its ribs and struts 31, 33 fromthe upstanding flanges of the tracks 66, as is the bottom tray in FIG.14. Tracks 66 are spaced just wider than the spacing of tray legs 41.Accordingly, tray legs 41 are within and embraced by the tracks flanges66 to prevent lateral movement, particularly during turning. Note thatthe tray legs are still elevated above the bottom flanges 83 of thetracks, even after the tray has settled to its position shown at thebottom of FIG. 4, the support for the tray being solely from the topedges of the flanges 66.

The egg trays 30 are removed from the racks 46 by reversing theprocedure just described. The sheet bed 77 of pallet 76 is inserted inthe space between tray legs 41 and bottom flanges 83 of track 66 andshoved inwardly. The trays 30 will be lifted slightly on the inclinedends 86 of the high flanges 81, so as to be transferred to the pallet'76. During this process the trays 30 will be held against longitudinalmovement by reason of abutment with the hanger bracket 65. As soon asall of the egg laden trays 30 on any one track have been transferred tothe pallet, it can simply be withdrawn as a unit to remove the trayedeggs therefrom, for example, when the eggs are transferred to thehatcher. It is not essential that the pallet 76 may be used as the trays30 can be inserted in the racks individually. However, the use of thepallet 76 speeds up the operation of loading and unloading the rack.

The Incubator Cabinet The incubator cabinet 47 is shown in FIGS. 15through 21. For the purpose of exemplification, an incubator cabinetadapted to receive twelve racks 46 is illustrated herein. In a practicalembodiment of the invention such a cabinet will occupy an area of 10feet by 27 feet, 4 inches and can incubate concurrently 77,760 eggs.Each of the egg racks 46 will contain 180 trays each containingthirty-six eggs. The racks 46 are desirably disposed in two rows eachalong the sides of the cabinet 47 with a central aisle 87 therebetween.The operator can walk along the aisle to inspect the eggs and makenecessary adjustments in the couplings to the egg turning motors as theracks are shifted from one state of incubation to the next.

At the input end of the cabinet there is a low pressure plenum chamber88, which also functions as an inlet passage through which the racks 46are wheeled through a doorway into the cabinet, as is shown in FIG. 15.The other or discharge end of the cabinet is provided with a highpressure. plenum chamber 89, which has a door 92 from which the eggracks may be withdrawn periodically.

The cabinet 47 is conveniently made of sheet metal and may have its ownfloor or simply rest upon the concrete or other floor93 of the buildingin. which it is located. Within the cabinet 47, floor 93 supports angletracks 53 on which the grooved rollers 52 of the racks 46 will ride. Thetracks have appropriately located switches 94 on which the direction ofmovement of the racks can be changed. The tracks in the cabinetaccurately maintain in alignment the racks 46 and guide them in theirmovement through the cabinet to avoid contact with the sides of thecabinet, jamming in the doorways, etc.

As shown in FIG. 22 each rack is provided with fluid coupling lines 95.These lines have conventional snap-on couplings 96 by which they arereadily coupled to the lines on next adjacent racks and to the fluidsupply lines 97 permanently fastened to the ceiling of the cabinet 47above the aisleway 87. The lines supply fluid pressure to the doubleacting fluid motors 67. The racks 46 are provided with keeper clips 98in which the lines 95 and couplings 96 are secured when the rack 46 isoutside of the cabinet and from which the lines are readily released forcoupling to the lines 97 or to the couplings of the next adjacent rack.The respective lines 96 are connected through the couplings 99 in eachrack to the respective ends of the double acting fluid motor 67. Ac-

cordingly, as the racks are moved through thecabinet 47 they are coupledone to the other for concurrent turning of their egg trays. The linesare flexible to accommodate movement and are readily uncoupled tofacilitate transfer of the racks to and from the cabinet.

Low pressure plenum chamber 88 is provided along a top corner thereofWith a series of blower fans 102 which circulate air throughout thecabinet 47 on the path indicated by the arrows in FIGS. 20 and 21. Thelow pressure plenum is provided with an inlet air port 103 and the highpressure plenum is provided with an outlet air port 104. Dampers 105,106, which concurrently are slidable across the ports 103, 104 tocorrespondingly change the degree of opening thereof are connected by anendless cable 107 having a chain section 110 driven from the sprocket108 on the damper control motor 109. The motor 109 is subject to atemperature controller which can be conventional or similar to the oneshown in my copending application Serial No. 654,828, filed April 24,1957, now US. Patent 3,056,533 granted October 2, 1962. Its detail neednot be repeated here. Essentially the controller is responsive to athermostat 114. When the thermostat calls for heat the heating element132 is energized and motor 109 is energized to move the dampers 105, 106toward closed position. When heat demand has been satisfied thecontroller will deenergize heating element 132 and reverse the motor 100to move the dampers 105, 106 toward open positions. The cycle of themotor is very slow. It takes thirtyeight minutes for it tomove thedampers between their extreme positions, even when constantly energizedto move in one direction. In normal operation it will reverseperiodically and the dampers 105, 106 will have a relatively narrowrange. This will depend on outside tem perature, how many eggs are inthe cabinet, etc. In my prior application aforesaid the heating elementis interlocked against energizations except when the damper is at itsminimum position. I prefer to omit the interlock in applying thecontroller to the incubator of the present invention. This is becausethe cabinet 47 herein is subject to sudden heat loss when the racks aretransferred and I wish the heater 132 to more quickly respond to thethermostat 114. I At the minimum open position of dampers 105, 106,there will be a 6 inch opening in the ports 103, 104, thus to admitsufiicient fresh air into the chamber 47 to supply the demaind of theeggs for oxygen, even when there is a demand for heat. If the dampersare opened beyond their minimum setting, additional outside air will bedrawn into the low pressure plenum 88, as shown by the arrows 112, andair in greater quantity will be discharged from the port 104 in the highpressure plenum 89, as shown by the arrows 113.

Accordingly, the temperature of the air within the cabinet 47 can beclosely controlled by adjusting the position of the dampers 105, 106 toadmit large or small quantities of outside air and concurrentlycontrolling the heat element 132. Auxiliary heat element 133 is providedwith its own thermostat 121 set at of a degree F. below thermostat 114,thus to furnish added heat it there is a radical heat drop in thecabinet.

In incubator operations the twelve racks 46 help channel the air flow asshown in FIGS. 20, 21. The tops 123 of the racks 46 form with the topWall of the cabinet 47 an air passage 124 shown in FIGS. 20, 21, alongwhich the air impelled by the fans 102 will travel to the high pressureplenum 89.

After entering the high pressure plenum 89, the air will follow the pathof the arrows shown in FIGS. 20, 21 and return to the low pressureplenum 88 through the racks 46 and will fiow over any eggs therewithinas shown in FIG. 19. While in the cabinet 47 the trays 30 are alwaystilted in the same direction. This is changed to the opposite directiononce per hour. In any event the eggs will be disposed with their majoraxes ata45 angle to the vertical by reason of the egg turning mechanismhereinbefore described, and the air will flow around the eggs, bothalong their major and minor axes, as indicatedby the arrows 125. Whenthe eggs are tilted, as shown in FIG. 19, they will ordinarily shiftslightly in the cradle ledges 35 to lean against and receive supportfrom the partitions 37. However,

the area of contact is extremely small and the air will freely pass overalmost the entire surface of the egg, the only egg surfaces which arenot exposed to a moving current of air being those surfaces in linecontact with the edges of the cradle ledges 35 and the tiny area on theegg side which touches the partition 37 against which .it rests.gAccordingly, practically all of the egg surface is exposed to thecirculating air. The exposure exceeds ninety-five percent.

When the egg turning mechanism tilts the trays 30 in the directionopposite to which they are shown in FIG. 19, the air will pass over theeggs at an incline to their major and minor axes, but in a directionjust opposite arrows 125. Regardless of the direction of incline theopen spaces 36, 39 in the egg tray 30 facilitate the flow of air aroundthe eggs.

To confine the air fiow through the interior rack portions which containthe eggs, the racks 46 have in addition to top wall 123 a bottom wall126 and one side wall 127 which is parallel to and next adjacent theside walls of the cabinet 47. The sides of the racks in the stream ofair are open and the side of the racks opposite wall 127 does not haveany permanent Wall, as it is desired that this side be open for loadingand inspection of the eggs. However, to confine the air flow within theinterior of the racks, canvas curtains 128 are hung at both sides of theaisle 87. Inasmuch as the insides of the racks 46 are exposed to the lowpressure plenum 88, the curtains will be drawn relatively tight againstthe aisle sides of the racks to substantially seal these sides of theracks.

The end of the aisle adjacent low pressure plenum 88 is sealed by thedoors 131. These doors may be opened to admit the operator to the aisle87 while the eggs are incubating.

Operation of Incubator Assuming a three day interval between the settingof each batch or stage of eggs in the incubator and the incubation ofchicken eggs which require eighteen days in the incubator. and anadditional three days in the hatchet, for a total incubation period oftwenty-one days, the incubator is initially put into operation on thefirst day of the incubation cycle by rolling fully loaded racks 46 offreshly laid eggs into incubator stations 115, as shown in FIG. 17.Under the assumed conditions aforesaid the racks 46 at the otherstations 116-120 will be empty of eggs. The two egg racks at opposite.sides or" the aisle at rack station will remain at station 115 for threedays and then are shifted longitudinally of the cabinet 47 into rackstation 116. This is done by rolling all the racks longitudinally of thecabinet on their tracks 53. The racks 46 formerly at egg rack stationare removed from the incubator through the door 92, and two additionalracks 46 with freshly set eggs are positioned at rack station 115 byrolling them into the incubator through the door of the low pressureplenum chamber 88, as shown in FIG. 15. Every three days, two racks offreshly set eggs are positioned at station 115 and the previously setand partially incubated eggs are transferred progressively from station116 through station 120.

When the incubator is completely filled with eggs, those eggs in theracks at station 115 will have been in the incubator from one to threedays, the eggs at station 116 will have been in the incubator from fourto six days, the eggs at station 117 will have been in the incubatorfrom seven to nine days, the eggs at station 118 willhave been in theincubator from ten to twelve days, the eggs at station 119 will havebeen in the incubator from 9 thirteen to fifteen days, and the eggs atstation 120 will have been in the incubator from sixteen to eighteendays. Those eggs in the incubator less than fourteen days are in theheat absorbing early stage and those in the incu bator more thanfourteen days will be in the heat releasing late stage.

After eighteendays when the racks at station 120 are removed from theincubator to make room for freshly set eggs at station 115, the eighteenday old eggs are removed from the trays 30 and are placed in a hatcher.The hatcher uses a different-kind of a tray in which the eggs are laidon their sides preparatory to hatch and in which the chicks can movearound after hatching. The incubator is now in full operation with eggsin six different positions, those nearest high pressure plenum 89 beinglate stage eggs and those nearest low pressure plenum 88 being earlystage eggs.

The air flow pattern shown in FIGS. 20, 21 and the periodic shifting ofthe racks longitudinally of the cabinet 47 against the flow of air is agreat advantage in the incubation method of the invention. Eggs in theearly stages of incubation require heat to maintain them at propertemperature while eggs in the late stages of incubation give off heat.Moreover, in the late stages of incubatiom eggs require more oxygen thanthose in the early stages of incubation. The air flow pattern of thepresent invention is such as to supply air having more oxygen to theeggsin the late stages of incubation and also transfers heat from the latestage eggs which are giving off heat to the eggs in the early stages ofincubation and which are absorbing heat. This technique materiallyreduces the heat load of the incubator.

Close control is here maintained over the temperature of the eggs in theseveral stages of incubation, as distinguished from prior artmulti-stage incubators in which it is possible only to control theaverage temperature. Precise control is achieved here without need forelaborate equipment simply because the air flow pattern is made toconform to the desired transfer of heat from late stage eggs to earlystage eggs.

For example, for chicken eggs, all eggs in the incubator should have aninternal temperature of 99.5 F. The late stage eggs at stations 119 and120 will have an external temperature of 100 F., because they are giving01f heat. The early stage eggs at stations 115-118 will have an externaltemperature of 99 F because they are absorbing heat. The control systemwill be responsive to the thermostat 114 to maintain the temperature ofthe air flowing in passage 124 at 99 F. As aforesaid, this is controlledby admission of cooling air through the inlet port 103 and the dischargeof heated air through the port 104 and by control of the electric heatelement 132 which is the low pressure chamber 88 and heat element 133,which is in the pasage 124. Inasmuchas all of the air which iscirculated, except that which is discharged through port 104, isrequired to flow through all of the racks in the pattern of FIGS. 20, 21in which the air successively flows over the eggs in racks 120, 119,118, 117, 116, 115 and into the low pressure plenum 88, the 99 air whichflows over the last stage eggs at 100 will pick up heat from the latestage eggs to drop their temperature toward the optimum 99.5 F. This airincreases its temperature above 995 and continues through the incubatorto flow over the early stage eggs. Accordingly, the air flow patternwill transfer heat from the late stage eggs to the early stage eggs. Theearly stage eggs at 99 F. will tend to increase in temperature toward99.5 F.

As is conventional, the air within the cabinet 47 is maintained at theproper humidity by disposing in the passage 124, Water pans 134 whichare beneath the water supply nozzles 135. Nozzles 135 are under controlof the humidistat 136, which has a wet bulb and a wick 137 in a waterpan 138 (FIG. 16) and a conventional control circuit to a valvesupplying the nozzles 135.

The cabinets 47 can be made of sheet metal or the like for erection inexisting buildings. Alternatively, special buildings can be erected toreceive the racks 46 and such buildings constructed with the exactdimensions necessary to receive racks 46 so that the walls of thebuilding itself function as a cabinet 47. In any case, the tracks 53 arelaid on the floor of the cabinet and the turning switches 94 areprovided in both the chambers 88, 89 to guide the racks in their changeof direction in the course of their movement through the incubator.

As shown in FIG. 25, the track switches 94 have four tapered lead insegments 141 which align with the tracks 53 and are disposed about acentral plateau 142 in which the wheel 52 of the rack is free to turn inany direction as urged by the operator. Accordingly, when rolled ontothe plateau 142, the caster wheels 52 will follow any track segment 141into which its groove 143 is urged. When away from any track 53 theungrooved portions of the wheel 52 will simply roll on the floor andfunction as a conventional caster wheel for transport of the rack.

The cabinet 47 is desirably insulated to minimize heat exchange with thesurrounding atmosphere.

While the method of invention is believed to be clear from the foregoingdisclosure it may be summarized as follows: Eggs in early and latestages of incubation are arranged serially along a path of airflow inwhich the air flows from the late stage eggs to the early stage eggs totransfer heat generated by late stage eggs to the early stage eggs whichare absorbing heat. The eggs are periodically shifted against the flowof air as freshly set eggs are added to the serial arrangement at theend of the airflow path and late stage eggs are removed from thebeginning of the airflow path. After the incubator cabinet has beencompletely filled with eggs, newly set eggs are added periodically, inthe foregoing example, once every three days, and the late stage eggsare concurrently removed.

I claim:

1. Apparatus for incubating eggs comprising a cabinet having a top,bottom, sidewalls and end walls, a row of horizontally movable egg rackswithin the cabinet, each rack being adapted to contain a plurality ofeggs all at the same stage of incubation with adjacent racks containingeggs in different stages of incubation in a series from early stage eggsin the rack at one end of the row to late stage eggs in the rack at theother end of the row and intermediate stage eggs in a rack intermediatethe said end racks, a low pressure plenum chamber at one end of thecabinet adjacent the said one end of the row and spacing said one end ofthe row from one end wall of the cabinet a distance at least equal tothe length of one rack and forming an egg rack passageway at least aswide as a rack, a high pressure plenum chamber at the other end of therow and spacing said other end of the row fiom the other end Wall of thecabinet a distance at least equal to the length of one rack and formingan egg rack passageway at least as wide as a rack, means defining an airflow passage from the high pressure plenum to the low pressure plenumlongitudinally of the cabinet through the racks in said row, meansdefining a return air passage longitudinally of the cabinet from the lowpressure plenum to the high pressure plenum, air impeller means forforcing the air to flow from the low pressure plenum to the highpressure plenum through said return air passage, and means on which saidracks are movable longitudinally of said cabinet and against thedirection of air flow therethrough, said low pressure plenum having arack inlet through which a rack containing freshly set eggs is admittedto the cabinet and added to said one end of the row, said high pressureplenum having a rack outlet through which a rack containing late stageeggs is removed from the said other end of the row and discharged fromthe cabinet.

2. The apparatus of claim 1 in which said rack inlet and rack outlet arein the side walls of the cabinet for addition and discharge of the racksin a direction which is transverse to the longitudinal axis of thecabinet.

3. The apparatus of claim 1 in which said egg racks are provided withegg trays on which the eggs are tilted with their major axes at anoblique angle to the flow of air through the racks, said trayscomprising skeletonized frames having egg support members contacting theeggs at spaced points thereon and open therebetween for flow of airthrough the trays and along the major and minor axes of the eggs.

4. Apparatus for incubating eggs comprising a cabi v net having a top,bottom, sidewalls and end walls, a row of horizontally movable egg rackswithin the cabinet, each rack being adapted to contain a plurality ofeggs all at the same stage of incubation with adjacent racks containingeggs in different stages of incubation in a series from early stage eggsin the rack at one end of the row to late stage eggs in the rack at theother end of the row and intermediate stage eggs in a rack intermediatethe said end racks, a low pressure plenum chamber at one end of thecabinet adjacent the said one end of the row and spacing said one end ofthe row from one end Wall of the cabinet, a high pressure plenum chamberat the other end of the row and spacing said other end of the row fromthe other end wall of the cabinet, means defining an air flow passagefrom the high pressure plenum to the low pressure plenum longitudinallyof the cabinet through the racks in said row, means defining a returnair passage longitudinally of the cabinet from the low pressure plenumto the high pressure plenum, air impeller means for forcing the air toflow from the low pressure plenum to the high pressure plenum throughsaid return air passage, and means on which said racks are movablelongitudinally of said cabinet and against the direction of air. flowtherethrough, said row of racks being disposed in close proximity to oneside wall of the cabinet, another row of racks similar to the said rowand disposed against the other side wall of the cabinet, an aislebetween said rows, curtains along the boundaries of said aisles, andmeans providing a floor beneath the eggs and a top over the eggs, saidracks being open adjacent the next proximate egg racks whereby tochannel air flow through the eggs in the racks.

5. The apparatus of claim 4 in which the means providing the top overthe eggs is spaced from the top wall of the cabinet to define said airreturn passage therebetween.

6. The apparatus of claim 1 in which the low pressure plenum chamber isprovided with an air-inlet port, the high pressure plenum chamber isprovided with an outlet port, and means for controlling the degree ofopening of said ports for selectiveadmission of fresh air into the lowpressure plenum chamber and exhaust of air from the high pressure plenumchamber.

. References Cited in the file of this patent UNITED STATES PATENTS1,262,860 Smith Apr. 16, 1918 2,086,813 Markey n July 13, 1937 2,176,484Blakeslee Oct. 17, 1939 2,255,036 Gedge Sept. 9, 1941 2,267,473 MarkeyDec. 23, 1941 2,281,339 Taggart Apr. 28, 1942 2,564,508 Seacat Aug. 14,1951 2,667,857 Smith Feb. 2, 1954 2,704,531 Bailey Mar. 22, 19552,791,199 Hamnett May 7, 1957 2,864,336 Hamnett Dec. 16, 1958 2,887,090v Cannon May 19, 1959 2,997,021 Bailey Aug. 22, 1961

1. APPARATUS FOR INCUBATING EGGS COMPRISING A CABINET HAVING A TOP,BOTTOM, SIDEWALLS AND END WALLS, A ROW OF HORIZONTALLY MOVABLE EGG RACKSWITHIN THE CABINET, EACH RACK BEING ADAPTED TO CONTAIN A PLURALITY OFEGGS ALL AT THE SAME STAGE OF INCUBATION WITH ADJACENT RACKS CONTAININGEGGS IN DIFFERENT STAGES OF INCUBATION IN A SERIES FROM EARLY STAGE EGGSIN THE RACK AT ONE END OF THE ROW TO LATE STAGE EGGS IN THE RACK AT THEOTHER END OF THE ROW AND INTERMEDIATE STAGE EGGS IN A RACK INTERMEDIATETHE SAID END RACKS, A LOW PRESSURE PLENUM CHAMBER AT ONE END OF THECABINET ADJACENT THE SAID ONE END OF THE ROW AND SPACING SAID ONE END OFTHE ROW FROM ONE END WALL OF THE CABINET A DISTANCE AT LEAST EQUAL TOTHE LENGTH OF ONE RACK AND FORMING AN EGG RACK PASSAGEWAY AT LEAST ASWIDE AS A RACK, A HIGH PRESSURE PLENUM CHAMBER AT THE OTHER END OF THEROW AND SPACING SAID OTHER END OF THE ROW FROM THE OTHER END WALL OF THECABINET A DISTANCE AT LEAST EQUAL TO THE LENGTH OF ONE RACK AND FORMINGAN EGG RACK PASSAGEWAY AT LEAST AS WIDE AS A RACK, MEANS DEFINING AN AIRFLOW PASSAGE FROM THE HIGH PRESSURE PLENUM TO THE LOW PRESSURE PLENUMLONGITUDINALLY OF THE CABINET THROUGH THE RACKS IN SAID ROW, MEANSDEFINING A RETURN AIR PASSAGE LONGITUDINALLY OF THE CABINET FROM THE LOWPRESSURE PLENUM TO THE HIGH PRESSURE PLENUM, AIR IMPELLER MEANS FORFORCING THE AIR TO FLOW FROM THE LOW PRESSURE PLENUM TO THE HIGHPRESSURE PLENUM THROUGH SAID RETURN AIR PASSAGE, AND MEANS ON WHICH SAIDRACKS ARE MOVABLE LONGITUDINALLY OF SAID CABINET AND AGAINST THEDIRECTION OF AIR FLOW THERETHROUGH, SAID LOW PRESSURE PLENUM HAVING ARACK INLET THROUGH WHICH A RACK CONTAINING FRESHLY SET EGGS IS ADMITTEDTO THE CABINET AND ADDED TO SAID ONE END OF THE ROW, SAID HIGH PRESSUREPLENUM HAVING A RACK OUTLET THROUGH WHICH A RACK CONTAINING LATE STAGEEGGS IS REMOVED FROM THE SAID OTHER END OF THE ROW AND DISCHARGED FROMTHE CABINET.